Dynamics of mode-locked nanolasers based on Hermite-Gaussian modes

TL;DR

This paper investigates the complex dynamical behaviors of Hermite-Gaussian modes in mode-locked nanolasers, revealing unique mode-locking properties and regimes influenced by gain competition and cavity design.

Contribution

It introduces a detailed model for HG mode dynamics in nanolasers, highlighting mode-locking independence from cavity length and analyzing various operational regimes.

Findings

Mode-locking with cavity-length-independent repetition rate.

Distinct regimes of Q-switching, Q-switched mode-locking, and cw mode locking.

Robust mode-locking achievable with spatially separated gain and absorber.

Abstract

The different dynamical behaviors of the Hermite-Gaussian (HG) modes of mode-locked nanolasers based on a harmonic photonic cavity are investigated in detail using a model based on a modified Gross-Pitaevskii Equation. Such nanolasers are shown to exhibit mode-locking with a repetition rate independent of the cavity length, which is a strong asset for compactness.The differences with respect to conventional lasers are shown to originate from the peculiar gain competition between HG modes, which is investigated in details. In the presence of a saturable absorber, the different regimes, i. e. Q-switching, Q-switched mode-locking, and continuous-wave (cw) mode locking, are isolated in a phase diagram and separately described. Mode-locking is found to be robust against phase-intensity coupling and to be achievable in a scheme with spatially separated gain and absorber.